I'm having problems while fetching data from columns which have more than 255 characters
I got such an error message:
Open Client Message:
Message number: LAYER = (1) ORIGIN = (4) SEVERITY = (1) NUMBER = (132)
Message String: ct_fetch(): user api layer: internal common library error: The bind of result set item 3 resulted in truncation.
It fetches only the first 255 rows and truncates the rest.
I have tried to imply below lines before ct_connect but didn't work
CS_BOOL boolv = CS_TRUE;
CS_RETCODE retcode2 = ct_capability ( *connection, CS_GET, CS_CAP_REQUEST, CS_WIDETABLES, &boolv);
here are some part of the code , do you have any suggestion
for (i = 0; i < num_cols; i++) {
/*
** Get the column description. ct_describe() fills the
** datafmt parameter with a description of the column.
*/
retcode = ct_describe(cmd, (i + 1), &datafmt[i]);
if (retcode != CS_SUCCEED) {
ex_error("ex_fetch_data: ct_describe() failed");
break;
}
/*
** update the datafmt structure to indicate that we want the
** results in a null terminated character string.
**
** First, update datafmt.maxlength to contain the maximum
** possible length of the column. To do this, call
** ex_display_len() to determine the number of bytes needed
** for the character string representation, given the
** datatype described above. Add one for the null
** termination character.
*/
datafmt[i].maxlength = ex_display_dlen(&datafmt[i]) + 1;
/*
** Set datatype and format to tell bind we want things
** converted to null terminated strings
*/
datafmt[i].datatype = CS_LONGCHAR_TYPE;
datafmt[i].format = CS_FMT_NULLTERM;
/*
** Allocate memory for the column string
*/
coldata[i].value = (CS_CHAR *) malloc(datafmt[i].maxlength);
if (coldata[i].value == NULL) {
ex_error("ex_fetch_data: malloc() failed");
retcode = CS_MEM_ERROR;
break;
}
/*
** Now bind.
*/
retcode = ct_bind(cmd, (i + 1), &datafmt[i], coldata[i].value,
&coldata[i].valuelen, (CS_SMALLINT *) &coldata[i].indicator);
if (retcode != CS_SUCCEED) {
ex_error("ex_fetch_data: ct_bind() failed");
break;
}
}
.............
.............
.............
/*
** Fetch the rows. Loop while ct_fetch() returns CS_SUCCEED or
** CS_ROW_FAIL
*/
while (((retcode = ct_fetch(cmd, CS_UNUSED, CS_UNUSED, CS_UNUSED,
&rows_read)) == CS_SUCCEED) || (retcode == CS_ROW_FAIL)) {
Even we have faced problem when we are using Sybase with Uniface,but uniface sybase driver has got a option which will truncate the data and save in some other table but while fetching we have to fetch data from all the tables.
When using the native jconn*.jar drivers you have to set the "?CHARSET=iso_1" parameter on the JDBC driver to connect to a Sybase server with a default charset of Roman 8, otherwise you see this 255 characters truncation issue.
Could this be the problem you are experiencing?
Related
I'm using "MariaDB Connector/C" for my homework, but I got a problem: I always get an empty string when I pass in a string parameter, the db table is:
MariaDB none#(none):test> SELECT * FROM t3
a
b
0
abc
1
bcd
2
af
3 rows in set
Time: 0.010s
MariaDB none#(none):test> DESC t3
Field
Type
Null
Key
Default
Extra
a
int(11)
NO
PRI
b
char(10)
YES
2 rows in set
Time: 0.011s
And the code I use to test:
#include <mysql/mysql.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main()
{
MYSQL *mysql;
mysql = mysql_init(NULL);
if (!mysql_real_connect(mysql,NULL , "none", "linux", "test", 0,"/tmp/mariadb.sock",0)){
printf( "Error connecting to database: %s",mysql_error(mysql));
} else
printf("Connected...\n");
if(mysql_real_query(mysql,"SET CHARACTER SET utf8",(unsigned int)sizeof("SET CHARACTER SET utf8"))){
printf("Failed to set Encode!\n");
}
char query_stmt_2[]="select * from t3 where b=?";
MYSQL_STMT *stmt2 = mysql_stmt_init(mysql);
if(mysql_stmt_prepare(stmt2, query_stmt_2, -1))
{
printf("STMT2 prepare failed.\n");
}
MYSQL_BIND instr_bind;
char instr[50]="abc";
my_bool in_is_null = 0;
my_bool in_error = 0;
instr_bind.buffer_type = MYSQL_TYPE_STRING;
instr_bind.buffer = &instr[0];
char in_ind = STMT_INDICATOR_NTS;
instr_bind.u.indicator = &in_ind;
unsigned long instr_len=sizeof(instr);
// instr_bind.length = &instr_len;
// instr_bind.buffer_length=instr_len;
instr_bind.is_null = &in_is_null;
instr_bind.error = &in_error;
MYSQL_BIND out_bind[2];
memset(out_bind, 0, sizeof(out_bind));
int out_int[2];
char outstr[50];
my_bool out_int_is_null[2]={0,0};
my_bool out_int_error[2]={0,0};
unsigned long out_int_length[2]={0,0};
out_bind[0].buffer = out_int+0;
out_bind[0].buffer_type = MYSQL_TYPE_LONG;
out_bind[0].is_null = out_int_is_null+0;
out_bind[0].error = out_int_error+0;
out_bind[0].length = out_int_length+0;
out_bind[1].buffer = outstr;
out_bind[1].buffer_type = MYSQL_TYPE_STRING;
out_bind[1].buffer_length = 50;
out_bind[1].is_null = out_int_is_null+1;
out_bind[1].error = out_int_error+1;
out_bind[1].length = out_int_length+1;
if(mysql_stmt_bind_param(stmt2, &instr_bind) ||
mysql_stmt_bind_result(stmt2, out_bind)){
printf("Bind error\n");
}
if(mysql_stmt_execute(stmt2))
{
printf("Exec error: %s",mysql_stmt_error(stmt2));
}
if(mysql_stmt_store_result(stmt2)){
printf("Store result error!\n");
printf("%s\n",mysql_stmt_error(stmt2));
}
while(!mysql_stmt_fetch(stmt2))
{
printf("%d\t%s\n", out_int[0], outstr);
}
mysql_stmt_close(stmt2);
end:
mysql_close(mysql);
}
I only got an empty result:
❯ ./Exec/test/stmt_test
Connected...
I have been in trouble with this for two days, and tomorrow is the deadline, I'm very anxious. Can you help? Thanks a lot!
1) General
Avoid "it was hard to write, so it should be hard to read" code
add variable declarations at the beginning of the function, not in the middle of code (Wdeclaration-after-statement)
don't use c++ comments in C
set character set with api function mysql_set_character_set()
write proper error handling, including mysql_error/mysql_stmt_error results and don't continue executing subsequent code after error.
always initialize MYSQL_BIND
2) input bind buffer
u.indicator is used for bulk operations and doesn't make sense here
bind.is_null is not required, since you specified a valid buffer address
buffer_length is not set (in comments)
3) Output bind buffer
Always bind output parameters after mysql_stmt_execute(), since mysql_stmt_prepare can't always determine the number of parameters, e.g. when calling a stored procedure: In this case mysql_stmt_bind_param will return an error.
binding an error indicator doesn't make much sense without setting MYSQL_REPORT_DATA_TRUNCATION (mysql_optionsv)
For some examples how to deal with prepared statements check the file ps.c of MariaDB Connector/C unit tests
I know that there probably was plenty on that but after several days of searching I am unable to find how to do one simple passing of integer and char in one go to PostgreSQL from C under Linux.
In PHP it is easy, like 123, and in C using libpq it seem to be like something out of ordinary.
I had a look at PQexecParams but is seem to be not helping. Examples on the net are not helping as well and it seems to be an impossible mission.
Would someone be kind enough to translate this simple PHP statement to C and show me how to pass multiple vars of different types in one INSERT query.
col1 is INT
col2 is CHAR
$int1 = 1;
$char1 = 'text';
$query = "INSERT INTO table (col1, col2) values ('$int1',$char1)";
$result = ibase_query($query);
This would show what I am trying to do (please mind the code is very wrong):
void insert_CommsDb(PGconn *conn, PGresult *pgres, int csrv0) { const char * params[1];
params[0] = csrv0;
pgres = PQexecParams(conn, "INSERT INTO comms_db (srv0::int) values ($1)",
1,
NULL,
params,
1,
NULL,
0);
if (PQresultStatus(pgres) != PGRES_COMMAND_OK)
{
fprintf(stderr, "INSERT failed: %s", PQerrorMessage(conn));
exit_nicely(conn,pgres);
}
PQclear(pgres);
}
https://www.postgresql.org/docs/current/static/libpq-exec.html
As #joop commented above:
If the paramTypes argument is NULL, all the params are assumed to be strings.
So, you should transform your int argument to a string.
void insert_CommsDb(PGconn *conn, int csrv0)
{
PGresult *pgres;
char * params[1];
char buff[12];
sprintf(buff, "%d", csrv0);
params[0] = buff;
pgres = PQexecParams(conn
, "INSERT INTO comms_db (srv0::int) values ($1)" // The query (we dont need the cast here)
, 1 // number of params
, NULL // array with types, or NULL
, params // array with parameter values
, NULL // ARRAY with parameter lenghts
, NULL // array with per-param flags indicating binary/non binary
, 0 // set to 1 if we want BINARY results, 0 for txt
);
if (PQrresultStatus(pgres) != PGRES_COMMAND_OK)
{
fprintf(stderr, "INSERT failed: %s", PQerrorMessage(conn));
exit_nicely(conn,pgres);
}
PQclear(pgres);
}
wildplasser's answer shows the way in general.
Since you explicitly asked about several parameters, I'll add an example for that.
If you are not happy to convert integers to strings, the alternative would be to use the external binary format of the data type in question. That requires inside knowledge and probably reading the PostgreSQL source. For some data types, it can also depend on the hardware.
PGresult *res;
PGconn *conn;
Oid types[2];
char * values[2];
int lengths[2], formats[2];
int arg0;
/* connect to the database */
/*
* The first argument is in binary format.
* Apart from having to use the "external binary
* format" for the data, we have to specify
* type and length.
*/
arg0 = htonl(42); /* external binary format: network byte order */
types[0] = 23; /* OID of "int4" */
values[0] = (char *) &arg0;
lengths[0] = sizeof(int);
formats[0] = 1;
/* second argument is in text format */
types[1] = 0;
values[1] = "something";
lengths[1] = 0;
formats[1] = 0;
res = PQexecParams(
conn,
"INSERT INTO mytab (col1, col2) values ($1, $2)",
2,
types,
(const char * const *)values,
lengths,
formats,
0 /* results in text format */
);
I'd recommend that you use the text format for most data types.
The notable exception is bytea, where it usually is an advantage to use the binary format, as it saves space and CPU power. In this case, the external binary format is simply the bytes.
VS C++ not liking htonl(42):
arg0 = htonl(42); /* external binary format: network byte order */
I am working on my own SNMP agent and am having trouble processing strings. I am pretty new to SNMP as well.
I've referred to the following links for some of implementing my own agent :
http://www.net-snmp.org/dev/agent/ucdDemoPublic_8c_source.html
http://www.net-snmp.org/dev/agent/example_8h_source.html
The second link shows exactly how to handle when a user attempts to set an integer type MIB object :
line 657 shows :
intval = *((long *) var_val);
My Question : How would I go about it with a string? I've tried casting it, strncpy, snprintf, etc.
My work :
I know, or at least think, that the following is legal :
int
setString(int action,
u_char * var_val,
u_char var_val_type,
size_t var_val_len,
u_char * statP, oid * name, size_t name_len)
{
unsigned char publicString[10];
static long intval;
char *cmd_string = NULL;
/*
* Define an arbitrary maximum permissible value
*/
switch (action) {
case RESERVE1:
//intval = *((long *) var_val);
/*
* Check that the value being set is acceptable
*/
if (var_val_type != ASN_OCTET_STR) {
DEBUGMSGTL(("setString", "%x not string type", var_val_type));
return SNMP_ERR_WRONGTYPE;
}
if (var_val_len > 1 ) {
DEBUGMSGTL(("setString", "wrong length %" NETSNMP_PRIz "u",
var_val_len));
return SNMP_ERR_WRONGLENGTH;
}
if ( !(var_val[0] == '1' || var_val[0] == '0') )
{
DEBUGMSGTL(("setString", "wrong value %s", var_val));
return SNMP_ERR_WRONGVALUE;
}
I know it is somewhat working because when I invoke
# snmpset -v 2c -c xxx 10.20.30.40 1.3.6.1.4.1.54321.3.0 s 3
Error in packet.
Reason: wrongValue (The set value is illegal or unsupported in some way)
Failed object: MY-TEST-MIB::testSnmp.3.0
AND
snmpset -v 2c -c xxx 10.20.30.40 1.3.6.1.4.1.54321.3.0 s 1
MY-TEST-MIB::testSnmp.3.0 = STRING: "1"
This proves to me at least the last collection of code is working.
Here is the action part :
case ACTION:
/*
* Set the variable as requested.
* Note that this may need to be reversed,
* so save any information needed to do this.
*/
if ( var_val[0] == '1' )
{
//do stuff - there realy is a script call here that does something
}
if ( var_val[0] == '0' )
{
//do stuff - there realy is a script call here that does something
}
break;
The above section I cannot get to work.
I've been able to get what I want by making the object an INTEGER (ASN.1) type but I can't do that because when reading this object it returns a STRING (ASN.1).
I've got stuck on my homework with SQLite. I use 2 columns; the first for product, the second for count. A user adds new products, which updates the count. We have to control, that the user doesn't add the same product again, or prevent him from picking more units than are available. We have to use it frequently, so I created functions:
int exists(char *param, sqlite3** ppDb) //0 if product exists
{
int error = 0;
char *a = NULL;
sqlite3_stmt **ppStmt = NULL;
const char **pzTail = NULL;
char *zSQL = sqlite3_mprintf("SELECT 'products' FROM 'table' WHERE 'products' LIKE '%q'", param);
//HERE IT FALS
error = sqlite3_prepare_v2(
*ppDb, /* Database handle */
zSQL, /* SQL statement, UTF-8 encoded */
(sizeof(zSQL)+1), /* Maximum length of zSql in bytes. */
ppStmt, /* OUT: Statement handle */
pzTail /* OUT: Pointer to unused portion of zSql */
);
sqlite3_free(zSQL);
a = (char*) sqlite3_column_text(*ppStmt, 0);
return strcmp(a, param); //0 if same -> product is in db yet
}
//similar one for count
Call
int main(int argc, const char *argv[])
{
sqlite3 *pDb;
int error = 0;
//parsing input
error = sqlite3_open(argv[1], &pDb);
if (error == 0)
{
sqlite3_exec(
pDb, /* An open database */
"CREATE TABLE 'table' ('products', 'quantity')", /* SQL */
0, /* Callback function */
NULL, /* 1st argument to callback */
NULL /* Error msg written here */
);
if (exists(param[1], &pDb) == 0)
{
fprintf (stderr, "ERROR: Product exists yet\n");
}
else
{
char *zSQL = sqlite3_mprintf("INSERT INTO 'table' VALUES ('%q', '0')", param[1]);
error = sqlite3_exec(
pDb, /* An open database */
zSQL, /* SQL to be evaluated */
0, /* Callback function */
NULL, /* 1st argument to callback */
NULL /* Error msg written here */
);
sqlite3_free(zSQL);
if (error == 0) printf("Added\n");
else printf("%i", error);
}
}
else return 1;
return 0;
}
It fails on sqlite3_prepare_v2. I expect there is a problem with the pointer on pDb, but I wasn't able to fix it (I'm not fan of pointers - too strong a tool for beginner). When it fails, the debugger stacked on line 93396 in sqlite3.c (*ppStmt = 0; - it writes somewhere, where it should'nt).
Compiled on linux x64:
gcc -std=c99 -Wall -pedantic -Wextra -Werror -DSQLITE_THREADSAFE=0 -ldl -o sqlite main.c sqlite3.c
Nothing wrong (if I've copied wrongly brackets, ignore it - it's not the problem), SQLite 3.7.14.1
Sorry for my English, I'm from Czech.
sqlite3_prepare_v2 wants to write the statement pointer into your output variable, but you are not giving it a pointer to this pointer variable, you are giving it a NULL pointer.
Use:
sqlite3_stmt *pStmt;
sqlite3_prepare_v2(..., &pStmt, ...);
Also note that identifiers should be quoted with "double quotes" or [brackets] or
`backticks`
but not with 'single quotes', which are used for literal strings.
I built a program that parses the header and I would like to read the message body in case I receive a POST.
For headers, I have been able to look for to determine when the header ends. I am having more issues for the message body. Am I supposed to look at "Content-Length" field to know when to stop reading input? In my current code (below), it will not stop until I hit the red cross (stop loading page) in Firefox.
Here is the code:
size_t n;
unsigned char newChar;
int index = 0;
int capacity = 50;
char *option = (char *) malloc(sizeof(char) * capacity);
while ( ( n = read( req->socket, &newChar, sizeof(newChar) ) ) > 0 ) {
if (newChar == '\0' || newChar == '\n') break; // This is not working
if (index == capacity) {
capacity *= 2;
option = (char *) realloc(option, sizeof(char) * capacity);
assert(option != NULL);
}
option[index++] = newChar;
fprintf(stderr, "%c", newChar);
}
if (index == capacity) {
capacity *= 2;
option = (char *) realloc(option, sizeof(char) * capacity);
assert(option != NULL);
}
option[index] = '\0';
The correct input gets printed, but I wonder why it won't stop until the stop loading button get pressed. I'd like to know if there is any other solution or if I please need to use the "Content-Length" field in the header.
Thank you very much,
Jary
There are a few things to consider. You'll want to consider how you want to handle all of these cases perhaps?
For HTTP protocol 1.0 the connection closing was used to signal the end of data.
This was improved in HTTP 1.1 which supports persistant connections. For HTTP 1.1 typically you set or read the Content-Length header to know how much data to expect.
Finally with HTTP 1.1 there is also the possibility of "Chunked" mode, you get the size as they come and you know you've reached the end when a chunk Size == 0 is found.
Also do you know about libcurl? It will certainly help you having to re-implement the wheel.
This code blocks on the read() waiting for another character which never comes.
Additionally, RFC2616, 3.7.1 states "HTTP applications MUST accept CRLF, bare CR, and bare LF as being representative of a line break in text media received via HTTP. In addition, if the text is represented in a character set that does not use octets 13 and 10 for CR and LF respectively, as is the case for some multi-byte character sets, HTTP allows the use of whatever octet sequences are defined by that character set to represent the equivalent of CR and LF for line breaks."
So you're going to need to catch more than just "\n".